Report 2014–5197

Prepared in cooperation with the New Mexico Interstate Stream Commission

Seepage Investigation on the Rio Grande from Below Caballo Reservoir, New Mexico, to El Paso, Texas, 2012

Scientific Investigations Report 2014–5197

U.S. Department of the Interior U.S. Geological Survey 2 1

Cover. 1. View of Westside Canal at Diversion at Mesilla Diversion Dam near Mesilla, New Mexico, June 27, 2012 (photograph by Jay Cederberg, U.S. Geological Survey). 2. View of Percha Dam recreation area at Caballo Lake State Park across Arrey Canal Diversion near Arrey, New Mexico, June 26, 2013 (photograph by Jay Cederberg, U.S. Geological Survey). 3. U.S. Geological Survey hydrologist Jay Cederberg conducting discharge measurement in Pence Lateral Wasteway 34A near Canutillo, Texas, June 28, 2012 (photograph by Rachel Powell, U.S. Geological Survey). 4. View downstream at Leasburg Main Canal near Radium Springs, New Mexico, June 27, 2012 (photograph by Jay Cederberg, U.S. Geological Survey). Seepage Investigation on the Rio Grande from Below Caballo Reservoir, New Mexico, to El Paso, Texas, 2012

By Mark A. Gunn and D. Michael Roark

Prepared in cooperation with the New Mexico Interstate Stream Commission

Scientific Investigations Report 2014–5197

U.S. Department of the Interior U.S. Geological Survey U.S. Department of the Interior SALLY JEWELL, Secretary U.S. Geological Survey Suzette M. Kimball, Acting Director

U.S. Geological Survey, Reston, Virginia: 2014

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Suggested citation: Gunn, M.A., and Roark, D.M., 2014, Seepage investigation on the Rio Grande from below Caballo Reservoir, New Mexico, to El Paso, Texas, 2012: U.S. Geological Survey Scientific Investigations Report 2014–5197, 17 p., http://dx.doi.org/10.3133/sir20145197.

ISSN 2328-0328 (online) iii

Acknowledgments

The authors gratefully acknowledge the generous assistance of Derrick O’Hara, Rio Grande Project of the Bureau of Reclamation; James Narvez, Elephant Butte Irrigation District; and Robert Rios, El Paso County Water Improvement District No. 1, for maintaining a constant state of the river and irrigation works during the measurements and providing their knowledge of the area and the irrigation system. The authors acknowledge Dr. Nabil Shafike for providing his review comments and assisting with initial planning efforts in the investigation. The authors also acknowledge assistance from Jerry Melendez, Bureau of Reclamation, with discharge measurements.

The authors acknowledge assistance from Jason Short, Anthony McGlone, Jay Cederberg, Lauren Sherson, Rachael Powell, Mike Carlson, Andrew Bernard, Patrick Swift, and John Summers, U.S. Geological Survey, with discharge measurements and Dianna Crilley, Anne Marie Matherne, Nicole Thomas, and Lauren Breitner, U.S. Geological Survey, for technical assistance. iv v

Contents

Abstract ...... 1 Introduction...... 1 Purpose and Scope...... 1 Description of the Study Area and Measurement Locations...... 2 Methods...... 2 Measurement of Surface-Water Discharge...... 2 Seepage Computation...... 10 Estimation of Uncertainty...... 10 Net Seepage Gain or Loss and Estimation of Uncertainty...... 10 Results of Seepage Investigation on the Rio Grande from Below Caballo Reservoir, New Mexico, to El Paso, Texas...... 11 Reach 1, Rio Grande Below Caballo Reservoir to Rio Grande at Haynor Bridge...... 11 Reach 2, Rio Grande at Haynor Bridge to Rio Grande Below Mesilla Diversion Dam...... 11 Reach 3, Rio Grande from Below Mesilla Diversion Dam to Rio Grande at Anthony–EP No. 1...... 11 Reach 4, Rio Grande at Anthony–EP No. 1 to Rio Grande at El Paso...... 15 Summary...... 17 References Cited...... 17

Figures

1. Map showing locations of U.S. Geological Survey Rio Grande discharge-measurement sites from below Caballo Reservoir, New Mexico, to El Paso, Texas, June 26–28, 2012...... 3 2. Diagram showing locations of U.S. Geological Survey Rio Grande discharge measurement sites from below Caballo Reservoir, New Mexico, to El Paso, Texas, June 26–28, 2012, and the relation of diversions, drains, and inflows to the river channel along the study reach...... 4 vi

Tables

1. Locations of U.S. Geological Survey Rio Grande discharge-measurement sites from below Caballo Reservoir, New Mexico, to El Paso, Texas, June 26–28, 2012...... 5 2. Field measurements and observations, Rio Grande seepage investigation, June 26–28, 2012...... 7 3. Summary of measured discharge and the computed net seepage gain or loss in Reach 1, Rio Grande seepage investigation, June 26, 2012...... 12 4. Summary of measured discharge and the computed net seepage gain or loss in Reach 2, Rio Grande seepage investigation, June 27, 2012...... 13 5. Summary of measured discharge and the computed net seepage gain or loss in Reach 3, Rio Grande seepage investigation, June 28, 2012...... 14 6. Summary of measured discharge and the computed net seepage gain or loss in Reach 4, Rio Grande seepage investigation, June 28, 2012...... 16 vii

Conversion Factors

Inch/Pound to SI

Multiply By To obtain Length foot (ft) 0.3048 meter (m) mile (mi) 1.609 kilometer (km) Area acre 4,047 square meter (m2) acre 0.4047 hectare (ha) acre 0.4047 square hectometer (hm2) acre 0.004047 square kilometer (km2) square foot (ft2) 929.0 square centimeter (cm2) square foot (ft2) 0.09290 square meter (m2) square mile (mi2) 259.0 hectare (ha) square mile (mi2) 2.590 square kilometer (km2) Volume acre-foot (acre-ft) 1,233 cubic meter (m3) acre-foot (acre-ft) 0.001233 cubic hectometer (hm3) Flow rate cubic foot per second (ft3/s) 0.02832 cubic meter per second (m3/s) foot per day (ft/d) 0.3048 meter per day (m/d)

SI to Inch/Pound

Multiply By To obtain Length millimeter (mm) 0.03937 inch (in.)

Temperature in degrees Celsius (°C) may be converted to degrees Fahrenheit (°F) as follows: °F=(1.8×°C)+32 Horizontal coordinate information is referenced to the North American Datum of 1983 (NAD 83). Specific conductance is given in microsiemens per centimeter at 25 degrees Celsius (µS/cm at 25 °C). Concentrations of chemical constituents in water are given in either milligrams per liter (mg/L) or micrograms per liter (µg/L). viii Seepage Investigation on the Rio Grande from Below Caballo Reservoir, New Mexico, to El Paso, Texas, 2012

By Mark A. Gunn and D. Michael Roark

Abstract The U.S. Geological Survey (USGS), in cooperation with the New Mexico Interstate Stream Commission, conducted A seepage investigation was conducted by the U.S. a seepage investigation on the Rio Grande from below Geological Survey, in cooperation with the New Mexico Caballo Reservoir, N. Mex., to El Paso, Tex., to determine Interstate Stream Commission, along an approximately streamflow loss or gain in this approximately 106-mile 106-mile reach of the Rio Grande from below Caballo reach of the Rio Grande. Increasing drought conditions have Reservoir, New Mexico, to El Paso, Texas, during June 26–28, resulted in reduced water available for domestic, agricultural, 2012, to determine gain or loss of streamflow due to seepage and recreational uses (Crilley and others, 2013). A better to or from the river channel. Discharge measurements were understanding of the spatial distribution of streamflow gains made during the irrigation season at high flow including 5 and losses during high flow conditions in this reach of the Rio sites along the Rio Grande, 5 diversions, and 63 inflows. The Grande is needed to better manage the available water. net gain or loss of flow in the river channel was computed The intent of the investigation was to determine gains for four reaches within the 106-mile reach of the Rio Grande. and losses from the river during a period of flows associated The normalized percentage difference was computed for with irrigation deliveries along the Rio Grande during the each reach to determine the difference between discharge summer of 2012 and to determine the component of those measured at upstream and downstream sites, and the gains and losses associated with surface-water/groundwater normalized percentage uncertainty was computed to determine interaction. Previous seepage investigations were conducted if a computed gain or loss exceeded cumulative uncertainty along portions of the study area during winter months by associated with measurement of discharge. measuring periods of base flow in the Rio Grande (Crilley and others, 2013).

Introduction Purpose and Scope The Rio Grande Compact (New Mexico State Annual § 75–34–3 (1953), Act of May 31, 1939, ch. 155, 53 This report describes the methods used to obtain Stat. 785), signed into law by Congress in 1938, apportions flow measurements and presents the results of the seepage the waters of the Rio Grande above Fort Quitman, Texas, investigation conducted on the Rio Grande between among the States of Colorado, New Mexico, and Texas and Caballo Reservoir, N. Mex., and El Paso, Tex., during June establishes water delivery obligations for Colorado and New 26–28, 2012. Discharge measurements at 73 sites, which Mexico and normal release for the Rio Grande below Elephant include 5 river sites, 5 irrigation diversions, and 63 inflow Butte Reservoir. The Bureau of Reclamation manages sites (50 irrigation return flows to the river, 8 drains, and Elephant Butte and Caballo Reservoirs, located on the Rio 5 wastewater treatment outfalls) are presented. The calculated Grande in New Mexico, for power supply and for irrigation streamflow gains and losses attributed to interactions with water supply. On the Rio Grande below Caballo Reservoir, groundwater along four reaches of the Rio Grande are also the Elephant Butte Irrigation District and El Paso County presented. Field measurements and observations recorded at Water Improvement District No. 1 operate and maintain a discharge measurement locations are presented and include system of irrigation canals and laterals that provides delivery water temperature, specific conductance, instantaneous of irrigation water to 90,640 acres of land within New Mexico discharge measurement, discharge measurement type, and and 68,000 acres within Texas (Bureau of Reclamation, 2008). discharge rating related to each site. 2 Seepage Investigation on the Rio Grande from Below Caballo Reservoir, New Mexico, to El Paso, Texas, 2012

Description of the Study Area and Measurement of Surface-Water Discharge Measurement Locations Discharge measurements at the sites during the seepage investigation were derived from field discharge The Rio Grande flows for 1,896 miles from measurements following standard USGS protocols (Rantz southwestern Colorado south through New Mexico, forming and others, 1982; Kilpatrick and Schneider, 1983; Nolan the international boundary between Texas and Mexico and Shields, 2000; Oberg and others, 2005; Turnipseed and outside the study area below El Paso, Tex. The study area Sauer, 2010) and from reported values from wastewater encompasses the lower third of the Rio Grande in New treatment plants. Surface-water depth and velocity were Mexico, a 106-mile reach from below Caballo Reservoir, N. determined primarily through the use of an acoustic Doppler Mex., to El Paso, Tex. (fig. 1). current profiler (ADCP) or an acoustic Doppler velocimeter Measurement locations included sites along the river (ADV) depending on site characteristics. The ADCP provides and all diversion and inflow locations that provided potential a continuous series of data throughout the cross section of gain or loss of streamflow to the river system. The river a channel, whereas the ADV measures point velocities at system includes the main channel, tributaries, and manmade 25–30 vertical sections that subdivide the channel such that features such as diversions and canals. River miles are no section contains more than 5 percent of the total cross- referenced upstream from site 69, at USGS streamgage Rio sectional discharge (Oberg and others, 2005). Discharge Grande at El Paso, which is designated as river mile 1,249.9 measurements were assigned a qualitative measurement (Hendricks, 1964). The relative locations of measurement uncertainty on the basis of field assessment of flow and sites are shown in figure 2, and associated river miles are measurement conditions of excellent (less than or equal to presented in table 1. 2 percent), good (less than or equal to 5 percent), fair (less than or equal to 8 percent), or poor (greater than 8 percent) (Turnipseed and Sauer, 2010). Multiple instantaneous discharge measurements were Methods made at river sites 1, 22, 41, 59, and 69 (table 2) throughout the duration of the investigation to monitor stability of flow The seepage investigation was conducted over a 3-day within the Rio Grande. Average values for each day and period in June 2012 during the irrigation season at high flow. reach were computed and used to calculate gain or loss Instantaneous discharge was measured at sites along the river within the respective reach. channel, at points of diversion, and at inflows along each Effluent from wastewater treatment plants that study reach. The net gain or loss of flow in the river channel discharged to the Rio Grande was reported as the daily mean was computed for four reaches along the Rio Grande (fig. discharge computed from the total discharge for the day 1). A reach is defined as the interval between two adjacent metered by the plant (reported-MDI) (table 2). Discharge river discharge-measurement locations. The reaches were data for all effluent sites are designated as “reported-MDI” designated as follows: Reach 1, Rio Grande below Caballo with an uncertainty in measurement greater than or equal Reservoir (site 1, river mile 1,355.6) to Rio Grande at to 8 percent, with the exception of site 10, which had no Haynor Bridge (site 22, river mile 1,322.5); Reach 2, Rio discharge during this investigation. Grande at Haynor Bridge (site 22, river mile 1,322.5) to Rio Specific conductance and water temperature were Grande below Mesilla Diversion Dam (site 41, river mile measured at all sites with multiparameter water-quality 1,285.7); Reach 3, Rio Grande below Mesilla Diversion Dam meters calibrated according to standard USGS protocols (site 41, river mile 1,285.7) to Rio Grande at Anthony–EP no. (Wilde and Radtke, variously dated) and are reported in 1 (site 59, river mile 1,265.9); and Reach 4, Rio Grande at table 2. Water temperature at site 69 was averaged for four Anthony–EP no. 1 (site 59, river mile 1,265.9) to Rio Grande measurements, each consisting of six cross-sectional transits at El Paso (site 69, river mile 1,249.9) (figs. 1 and 2; table 1). of the channel (table 2). Specific conductance at site 69 was Gains or losses in the river can result from seepage to averaged for five measurements, each consisting of six cross- or from the streambed, bank storage, or evaporation from sectional transits of the channel. Water quality parameters the water surface. Releases from Caballo Reservoir were were collected to verify field conditions to enable ADCPs and maintained at a constant rate during the study to minimize ADVs to compute the speed of sound correctly to accurately gains or losses from bank storage (Jay Powell, Bureau of measure velocities, depths, and compute discharge (Rantz Reclamation, oral commun., May 24, 2012). and others, 1982). Methods 3

107°20' 107°10' 107°00' 106°50' 106°40' 106°30' 106°20' 33°00'

Caballo Reservoir 3A 1 CABALLO DAM 3 32°50' 4 5 6 7 8 11 9 13 14 32°40' 10 12 19 15 16 20 1718 R io 21

22 G r a 23 n d e LEASBURG DAM 32°30' 24 25 Leasburg 26 27 28 25 ¤£70 29 30 32°20' 31 EXPLANATION 33 32 Las Cruces 34 Study reach of the Rio Grande 35 from below Caballo Reservoir, 10 36A 36 New Mexico to El Paso, Texas 37 38 39 41 Reach 1 40 42 MESILLA DIVERSION DAM 43 Reach 2 32°10' 44A Reach 3 44 4546 47 Reach 4 48 49 50 Discharge-measurement site 51 5 52 NEW MEXICO and identification number 53 54 55 56 57 32°00' 56A Anthony 58 59 59A 60 TEXAS 61 62 63 COLORADO 64 31°50' 65 68 e 66 69 d n UNITED STATES 67 El Paso a Elephant Butte r AMERICAN DAM G MEXICO 10 Reservoir NEW o i MEXICO Caballo R Reservoir TEXAS Fort Quitman Base from U.S. Geological Survey digital data U Universal Transverse Mercator, zone 13 Area enlarged NITE D North American Datum of 1983 S MEXICOT A T E S 0 10 20 30 MILES

0 10 20 30 KILOMETERS

Figure 1. Locations of U.S. Geological Survey Rio Grande discharge-measurement sites from below Caballo Reservoir, New Mexico, to El Paso, Texas, June 26–28, 2012. laf13-0569_fig 01 4 Seepage Investigation on the Rio Grande from Below Caballo Reservoir, New Mexico, to El Paso, Texas, 2012

1,360 1,330 1,300 1,270 55 17 18 30 56A 56 57 19 58

31 59A 1 59 20 32 1,355 1,325 1,295 1,265 60 3A 3 61

21 33 34 22 35 36/36A 4

1,350 1,320 23 1,290 1,260

37 62 63 39 38 64 5 40

65 41 1,345 1,315 1,285 1,255 6 66 42 43

7 44/44A

Distance along the Rio Grande, in river miles 67 45 68 1,340 1,310 24 1,280 46 1,250 69

8 25

9 47

10 11 12 13 48 1,335 1,305 1,275 1,245 26 50 49 14 27 15

28 52 16 1,330 1,300 29 1,270 53 54 1,240

River miles are referenced upstream from the Rio Grande at EXPLANATION El Paso, Texas, which is designated as river mile 1,249.9 (Hendricks, 1965). Inflow Reach 1 Diversion Reach 2 River Reach 3 69 Discharge-measurement site and identification number Reach 4

Figure 2. Locations of U.S. Geological Survey Rio Grande discharge-measurement sites from below Caballo Reservoir, New Mexico, to El Paso, Texas, June 26–28, 2012, and the relation of diversions, drains, and inflows to the river channel along the study reach. Methods 5

Table 1. Locations of U.S. Geological Survey Rio Grande discharge-measurement sites from below Caballo Reservoir, New Mexico, to El Paso, Texas, June 26–28, 2012.

[ID, identification number; USGS, U.S. Geological Survey; NAD 83, NorthAmerican Datum of 1983; WW, wasteway]

Latitude Longitude Site ID USGS station ID Station name River mile1 (NAD 83) (NAD 83) 1 8362500 Rio Grande below Caballo Dam 32.88492 -107.29269 1,355.6 3 325205107181110 Percha Lateral Diversion 32.86811 -107.30308 1,354.5 3A 325208107181810 Arrey Canal Diversion 32.86900 -107.30514 1,354.3 4 325011107175710 Trujillo Lateral WW 32.83636 -107.29906 1,351.2 5 324714107175610 Vega Lateral WW 3B 32.78722 -107.29889 1,347.1 6 324531107165810 Gonzales Lateral WW 3 32.75858 -107.28269 1,344.3 7 324416107164310 Palmer Lateral WW 4 32.73778 -107.27853 1,342.4 8 324208107144910 Garfield/Hatch Canal WW 5 32.70222 -107.24700 1,339.0 9 324147107134910 WW6A 32.69631 -107.23033 1,337.8 10 324137107123310 Dona Anna Sewage Outfall 32.69369 -107.20906 1,336.6 11 324133107122010 Unnamed WW 32.69253 -107.20558 1,336.4 12 324106107120810 Unnamed WW (A) 32.68503 -107.20222 1,335.8 13 324115107113710 Garfield Drain 32.68758 -107.19353 1,335.3 14 324047107101610 H-2 Lateral 32.67972 -107.17097 1,333.9 15 324028107100310 Hatch Canal WW 13 32.67447 -107.16739 1,333.5 16 324000107071410 Hatch Canal WW 16 32.66678 -107.12053 1,330.6 17 323910107062010 Hatch Drain 32.65275 -107.10542 1,329.3 18 323916107055710 Angostura Lateral WW 14 32.65458 -107.09914 1,328.9 19 323926107040910 WW17 32.65714 -107.06922 1,327.2 20 323832107024210 Angostura Lateral WW 15 32.64225 -107.04492 1,325.3 21 323723107012810 Rincon Canal WW 18 32.62317 -107.02453 1,323.2 22 323649107011410 Rio Grande at Haynor Bridge 32.61344 -107.02053 1,322.5 23 323516106595110 Tonuco Intercepting Drain 32.58769 -106.99764 1,320.1 24 322920106552010 Leasburg Main Canal Diversion 32.48897 -106.92219 1,310.0 25 322850106551510 Leasburg Lateral WW 1 32.48067 -106.92094 1,300.0 26 322541106525210 Selden Drain 32.42800 -106.88097 1,308.8 27 322536106522210 American Bend Lateral WW 2 32.42658 -106.87278 1,304.4 28 322334106514010 Hill Lateral WW 2A 32.39281 -106.86114 1,303.9 29 322241106512810 Picacho WW 3 32.37808 -106.85764 1,301.5 30 322215106501410 Leasburg Lateral WW 5 32.37075 -106.83722 1,298.6 31 322032106493110 Leasburg Extension Lateral WW 8 32.34208 -106.82528 1,296.2 32 321923106500410 Picacho A Lateral WW 39A 32.32308 -106.83458 1,295.1 33 321744106492310 Mesilla Lateral WW 11 32.29567 -106.82294 1,293.1 34 321736106492410 City of Las Cruces Wastwater 32.29325 -106.82328 1,292.9 35 321639106493010 WW12 32.27750 -106.82508 1,291.8 36 321605106494710 Picacho Lateral WW 40 32.26814 -106.82978 1,291.2 36A 321603106500610 Picacho Drain 32.26747 -106.83497 1,291.2 37 321431106484710 California Lateral WW 13 32.24183 -106.81294 1,289.1 38 321342106474610 Eastside Canal at Diversion 32.22842 -106.79617 1,287.6 39 321332106474910 Westside Canal at Diversion 32.22564 -106.79706 1,287.6 40 321327106472610 Del Rio Lateral WW 14A 32.22406 -106.79047 1,287.2 41 321237106462010 Rio Grande below Mesilla Diversion Dam 32.21028 -106.77186 1,285.7 6 Seepage Investigation on the Rio Grande from Below Caballo Reservoir, New Mexico, to El Paso, Texas, 2012

Table 1. Locations of U.S. Geological Survey Rio Grande discharge-measurement sites from below Caballo Reservoir, New Mexico, to El Paso, Texas, June 26–28, 2012.—Continued

[ID, identification number; USGS, U.S. Geological Survey; NAD 83, NorthAmerican Datum of 1983; WW, wasteway]

Latitude Longitude Site ID USGS station ID Station name River mile1 (NAD 83) (NAD 83) 42 321151106444310 Del Rio Lateral WW 14B 32.19756 -106.74533 1,283.9 43 321132106441310 Eastside Lateral WW 15 32.19219 -106.73703 1,283.3 44 321016106431310 Santo Tomas River Drain 32.17108 -106.72033 1,281.5 44A 321014106431210 Santa Tomas River Lateral WW 25 or 14 32.17069 -106.72014 1,281.5 45 320936106430310 Wasteway 26 32.16014 -106.71761 1,280.7 46 320928106423010 Brazito River Lateral WW 16B 32.15767 -106.70831 1,280.1 47 320757106403910 WW 18 32.13250 -106.67758 1,277.5 48 320615106393310 Del Rio Drain 32.10414 -106.65914 1,275.2 49 320525106393610 Dona Ana County Wastewater 32.09031 -106.65994 1,274.3 50 320523106391710 Three Saints Main Canal WW 19 32.08983 -106.65461 1,274.2 51 320354106395010 Chamberino East Lateral WW 30 32.06511 -106.66397 1,272.4 52 320214106392810 La Mesa Drain 32.03722 -106.65769 1,270.5 53 320215106395110 La Union Main Canal WW 31 32.03739 -106.66406 1,270.4 54 320210106385510 Three Saints West Lateral WW 20 32.03611 -106.64856 1,270.2 55 320122106385610 Anthony Wastewater 32.02289 -106.64878 1,269.3 56 320027106381810 Three Saints West Lateral WW 21 32.00744 -106.63847 1,268.0 56A 320019106383410 Jiminez Lateral WW 31B 32.00519 -106.64281 1,268.0 57 315957106380610 Pipe inflow at NM-225 Bridge 31.99928 -106.63531 1,267.4 58 315942106380810 La Union East Lateral WW 32 31.99508 -106.63561 1,267.1 59 315853106371510 Rio Grande at Anthony-EP no. 1 31.98153 -106.62106 1,265.9 59A 315849106371610 Rowley Lateral 31.98036 -106.62122 1,265.9 60 315808106362010 Texas Lateral WW 23A 31.96897 -106.60556 1,264.7 61 315733106362310 Vinton Cut-off Lateral WW 32B 31.95917 -106.60642 1,264.0 62 315256106360310 Canutillo Lateral WW 34 31.88225 -106.60078 1,258.6 63 315229106361610 Pence Lateral WW 34A 31.87472 -106.60453 1,258.0 64 315208106363410 La Union East Lateral 31.86900 -106.60956 1,257.6 65 315047106362410 Schultz Lateral WW 35C 31.84631 -106.60669 1,256.0 66 314924106355410 Montoya A Lateral WW 36 31.82319 -106.59833 1,254.1 67 314755106332510 Sunland Park Wastewater 31.79867 -106.55703 1,250.9 68 314808106325310 Montoya Drain 31.80233 -106.54800 1,250.3 69 08364000 Rio Grande at El Paso 31.80289 -106.54083 1,249.9 1River miles are referenced upstream from the Rio Grande at El Paso, Texas, which is designated as river mile 1,249.9 (Hendricks, 1964). Methods 7

Table 2. Field measurements and observations, Rio Grande seepage investigation, June 26–28, 2012.

[ID, identification number; site ID: see table 1 and figures 1 and 2 for location of sites. °C, degrees Celsius; μS/cm, microsiemens per centimeter; ft³/s, cubic foot per second ; ──, not applicable; ADCP, acoustic Doppler current meter; ADV, acoustic Doppler velocimeter; EST, estimate; reported-MDI, instantaneous discharge computed from the reported mean daily total discharge; E, excellent (within 2 percent); G, good (within 5 percent); F, fair (within 8 percent); P, poor (greater than 8 percent); U, unspecified (rated as fair, within 8 percent); LB, left bank; RB, right bank; Av, measurement average]

Instantaneous Water Specific Discharge Sample time discharge Discharge Site ID Sample date temperature conductance at measurement (military) measurement rating (°C) 25 °C (μS/cm) type (ft³/s) 1 6/26/2012 1037 23.1 ── 1,680 ADCP G 1 6/26/2012 1146 24.1 ── 1,670 ADCP G 1 6/26/2012 1251 24.1 ── 1,660 ADCP G 3 6/26/2012 0900 ── ── ── ── E 3 6/26/2012 1047 ── ── ── ── E 3A 6/26/2012 0921 22.7 ── 187 ADCP G 3A 6/26/2012 1014 ── ── 192 ADCP G 4 6/26/2012 1000 ── ── ── ── E 5 6/26/2012 1015 ── ── ── E 6 6/26/2012 1025 24.5 752 0.08 EST F 7 6/26/2012 1035 21.8 1,310 0.01 EST F 8 6/26/2012 1045 24.9 746 0.55 EST P 9 6/26/2012 1100 ── ── ── ── E 10 6/26/2012 1105 ── ── ── ── E 11 6/26/2012 1113 ── ── ── ── E 12 6/26/2012 1108 ── ── ── ── E 13 6/26/2012 1111 ── ── ── ── E 14 6/26/2012 1117 ── ── ── ── E 15 6/26/2012 1145 25.8 723 4.76 ADV F 16 6/26/2012 1210 26.2 745 0.10 ADV F 17 6/26/2012 1221 ── ── ── ── E 18 6/26/2012 1225 ── ── ── ── E 19 6/26/2012 1222 ── ── ── ── E 20 6/26/2012 1230 ── ── ── ── E 21 6/26/2012 1224 ── ── 0.25 EST P 22 6/26/2012 0951 24.0 738 1,420 ADCP G 22 6/26/2012 1059 24.3 732 1,410 ADCP G 22 6/26/2012 1142 ── ── 1,420 ADCP G 22 6/26/2012 1209 24.8 735 1,410 ADCP G 22 6/26/2012 1301 ── ── 1,430 ADCP G 22 6/27/2012 0859 23.4 738 1,390 ADCP F 22 6/27/2012 0944 23.5 735 1,420 ADCP G 22 6/27/2012 1027 23.8 721 1,390 ADCP G 22 6/27/2012 1115 24.1 732 1,390 ADCP G 22 6/27/2012 1208 24.4 731 1,420 ADCP G 22 6/27/2012 1251 24.7 731 1,400 ADCP G 22 6/27/2012 1328 25.1 726 1,400 ADCP G 22 6/27/2012 1402 25.3 726 1,400 ADCP G 8 Seepage Investigation on the Rio Grande from Below Caballo Reservoir, New Mexico, to El Paso, Texas, 2012

Table 2. Field measurements and observations, Rio Grande seepage investigation, June 26–28, 2012.—Continued

Instantaneous Water Specific Discharge Sample time discharge Discharge Site ID Sample date temperature conductance at measurement (military) measurement rating (°C) 25 °C (μS/cm) type (ft³/s) 22 6/27/2012 1440 25.6 729 1,400 ADCP G 22 6/27/2012 1512 25.8 731 1,410 ADCP G 22 6/27/2012 1550 26.1 732 1,410 ADCP G 22 6/27/2012 1632 26.3 734 1,390 ADCP G 23 6/27/2012 0900 19.1 1,933 2.46 EST P 24 6/27/2012 1135 24.9 730 193 ADCP G 25 6/27/2012 1128 ── ── ── ── E 26 6/27/2012 1222 ── ── ── ── P 27 6/27/2012 1230 ── ── ── ── E 28 6/27/2012 1240 28.2 701 0.34 EST F 29 6/27/2012 1128 25.0 744 4.64 ADV P 30 6/27/2012 1320 ── ── ── ── E 31 6/27/2012 1333 27.0 753 1.36 ADV P 32 6/27/2012 1400 ── ── ── ── E 33 6/27/2012 1405 ── ── ── ── E 34 6/27/2012 1410 28.7 1,305 7.00 EST P 35 6/27/2012 1420 27.8 750 0.25 EST P 36 6/27/2012 1431 26.6 1,033 5.32 ADV F 36A 6/27/2012 1510 ── ── ── ── E 37 6/27/2012 1242 ── ── ── ── E 38 6/27/2012 1317 27.0 ── 172 ADCP G 39 6/27/2012 1624 28.7 732 437 ADCP G 40 6/28/2012 0957 ── ── ── ── E 41 6/27/2012 1027 24.8 750 364 ADCP P 41 6/27/2012 1128 25.6 751 408 ADCP P 41 6/27/2012 1250 26.7 754 404 ADCP P 41 6/27/2012 1414 28.1 753 366 ADCP P 41 6/27/2012 1630 28.7 754 382 ADCP P 41 6/28/2012 0953 24.8 757 353 ADCP F 41 6/28/2012 1050 25.5 753 351 ADCP F 41 6/28/2012 1146 26.3 754 354 ADCP F 41 6/28/2012 1256 27.0 757 352 ADCP F 41 6/28/2012 1344 27.8 754 361 ADCP F 41 6/28/2012 1449 28.7 753 334 ADCP F 41 6/28/2012 1549 29.5 751 334 ADCP F 41 6/28/2012 1642 29.8 755 318 ADCP F 42 6/28/2012 1006 ── ── ── EST E 43 6/28/2012 1010 24.5 776 0.25 EST P 44 6/28/2012 1023 ── ── ── EST E 44A 6/28/2012 1022 22.9 728 0.12 EST P Methods 9

Instantaneous Water Specific Discharge Sample time discharge Discharge Site ID Sample date temperature conductance at measurement (military) measurement rating (°C) 25 °C (μS/cm) type (ft³/s) 45 6/28/2012 1028 25.5 759 0.42 EST P 46 6/28/2012 1036 25.6 772 1.00 EST P 47 6/28/2012 1045 26.3 713 0.25 EST P 48 6/28/2012 1053 ── ── ── ── E 49 6/28/2012 1106 29.1 1,340 6.00 Reported-MDI P 50 6/28/2012 1120 26.9 775 0.03 EST P 51 6/28/2012 1115 ── ── ── ── E 52 6/28/2012 1135 ── ── ── ── E 53 6/28/2012 1138 ── ── ── ── E 54 6/28/2012 1145 26.6 782 0.01 EST P 55 6/28/2012 1150 29.2 2,094 1.50 Reported-MDI P 56 6/28/2012 1156 ── ── ── ── E 56A 6/28/2012 1210 22.9 769 0.02 EST P 57 6/28/2012 1132 29.3 66 0.01 EST P 58 6/28/2012 1013 26.4 745 9.39 ADV G 59 6/28/2012 1149 27.8 738 395 ADCP F 59 6/28/2012 1231 28.3 771 394 ADCP F 59 6/28/2012 1302 29.0 760 397 ADCP F 59 6/28/2012 1335 29.6 760 385 ADCP F 59 6/28/2012 1409 30.2 767 393 ADCP F 59 6/28/2012 1442 30.7 770 396 ADCP F 59 6/28/2012 1519 31.3 771 392 ADCP F 59 6/28/2012 1559 31.7 772 399 ADCP F 59 6/28/2012 1632 31.9 776 405 ADCP F 59 6/28/2012 1709 32.0 779 413 ADCP F 59A 6/28/2012 1009 ── ── ── ── E 60 6/28/2012 1201 28.7 725 3.21 ADV G 61 6/28/2012 1257 ── ── ── ── E 62 6/28/2012 1305 27.4 741 3.66 ADV G 63 6/28/2012 1315 28.2 742 3.62 ADV G 64 6/28/2012 1416 26.7 823 11.0 ADV G 65 6/28/2012 1433 ── ── ── ── E 66 6/28/2012 1445 28.6 789 6.36 ADV P 67 6/28/2012 1500 ── ── ── ── E 68 6/28/2012 1700 31.2 345 8.88 ADCP P 69 6/28/2012 1020 25.4 (Av) 822 (Av) 399 ADCP F 69 6/28/2012 1125 26.3 (Av) 814 (Av) 393 ADCP F 69 6/28/2012 1203 26.0 875 388 ADCP F 69 6/28/2012 1232 28.4 873 385 ADCP F 69 6/28/2012 1334 29.4 781 (Av) 385 ADCP F 69 6/28/2012 1417 30.0 900 383 ADCP F 69 6/28/2012 1526 30.5 (Av) 746 (Av) 376 ADCP F 69 6/28/2012 1619 30.5 (Av) 796 (Av) 370 ADCP F 69 6/28/2012 1656 30.8 872 370 ADCP F 10 Seepage Investigation on the Rio Grande from Below Caballo Reservoir, New Mexico, to El Paso, Texas, 2012

Seepage Computation 2 22 δQa=±()⋅Qa+±()⋅Qa…+()±⋅Q (2) The mass balance equation used for calculating net Gn11 22 n seepage gain or loss in a reach is as follows (Simonds and Sinclair, 2002): where

δQG is the absolute value of the cumulative QQGd�=−siQQnu−+s Qout (1) measurement uncertainty in the where computation of seepage gain or loss, in cubic feet per second; QG is the net seepage gain or loss for a reach, in cubic feet per second; a1, a2,... an is measurement uncertainty, in percent; and Q , Q ,... Q is the measured discharge, in cubic feet per Qds is the discharge measured at the downstream 1 2 n end of the reach, in cubic feet per second; second. A gain or loss was determined to be substantial when it Qin is the sum of inflows, in cubic feet per second;

Qus is the discharge measured at the upstream end exceeded the cumulative uncertainty associated with the net of the reach, in cubic feet per second; and seepage computation.

Qout is the sum of the outflows, in cubic feet per second. The result is the estimated net flux of water gained or lost Net Seepage Gain or Loss and Estimation from the river for the reach. Positive values indicate a gaining of Uncertainty reach, and negative values indicate a losing reach. If Qds is greater than Qus plus Qin minus Qout, then the algebraic sign of the estimated flux is positive (+), which signifies a gain for Wilberg and others (2001) developed a technique used to determine if the difference between discharge measured at that reach. Conversely, if Qds is less than Qus plus Qin minus upstream and downstream sites in a specified reach exceeded Qout (that is, if less discharge was measured at the downstream section of the reach than was measured at the upstream section the cumulative measurement uncertainty at those sites. Each plus any inflow to that reach and minus any outflows [equation reach was normalized to the maximum discharge within that 1]), then the algebraic sign of the estimated flux in equation reach to allow for comparison between reaches with varying 1 is negative (-), which signifies a loss. discharges. These computations, as modified from Wilberg and Stolp (2005), are as follows: Estimation of Uncertainty QG The percentage of uncertainty for individual discharge Nd =×100 MaxQ (3) measurements was determined by a qualitative evaluation ()QQus + in ()QQds + out  of the measurement uncertainty and a subjective evaluation by the hydrographer considering objective factors that could where affect measurement quality (Sauer and Meyer, 1992). These Nd is the normalized seepage difference, in factors include number and distribution of vertical sections percent; and where velocity is measured, average velocity, uniformity of MaxQ is the maximum discharge measured along a flow, regularity and firmness of channel bottom, steadiness reach as either the downstream discharge of stage and discharge during the measurement, and presence plus any outflow or the upstream discharge or absence of ice, wind, or debris in the flow that could affect plus any inflow, in cubic feet per second. the ability of the current meter to accurately measure the current velocity (Wilberg and Stolp, 2005). If a site had zero flow (dry channel), then the uncertainty for that individual measurement was 0, and the uncertainty for that measurement δQ =± G × did not contribute numerically to the cumulative uncertainty Ne 100 (4) MaxQ()QQ+ ()QQ+  estimation for the reach. For purposes of computation, the  us in ds out  uncertainty in the measurement of discharge was assigned a numerical value as follows: dry channel, 0 percent; where excellent, 2 percent; good, 5 percent; fair, 8 percent; and Ne is the normalized cumulative uncertainty, in poor, 10 percent. percent. The cumulative measurement uncertainty estimation A computed loss or gain for a reach is considered associated with the computed net seepage gain or loss for a substantial if the normalized percentage difference (Nd%) reach was determined by the following equation (Wheeler and was greater than or equal to the normalized percentage

Eddy-Miller, 2005): uncertainty (Ne%). Results of Seepage Investigation on the Rio Grande from Below Caballo Reservoir, New Mexico, to El Paso, Texas 11

Results of Seepage Investigation Reach 2, Rio Grande at Haynor Bridge (Site 22) on the Rio Grande from Below to Rio Grande Below Mesilla Diversion Dam (Site 41) Caballo Reservoir, New Mexico, to Reach 2 consists of 36.8 miles along the Rio Grande El Paso, Texas and includes sites 22 to 41 beginning at Haynor Bridge and ending below Mesilla Diversion Dam (fig. 1). Of the The seepage investigation focused on a 106-mile reach 21 measurement locations, a total of 12 sites had measurable of the Rio Grande and included 73 measurement locations discharge (2 river, 3 diversion, and 7 inflow sites; table 4), from site 1 below Caballo Reservoir, N. Mex., to site 69, the with specific conductance and water temperature measured at Rio Grande at El Paso streamgage, in Texas (fig. 1; table 1). each site (table 2). Zero flow was observed at 9 inflow sites. Releases and diversions were coordinated with the Bureau of Uncertainty in the measurement of discharge was good Reclamation, Elephant Butte Irrigation District, and El Paso at sites 22, 24, 38, and 39 (table 2). All measured inflow County Water Improvement District No. 1 to provide stable sites were rated fair to poor. Site 28 was not assigned any flow conditions during the course of the investigation. Of the measurement uncertainty at the time of collection and was 73 measurement locations, a total of 39 sites had measurable categorized as unspecified; site 28 was categorized as fair discharge (5 river sites, 4 diversions, and 30 inflow sites), for the purpose of analysis on the basis of the discharge and with specific conductance and water temperature measured channel conditions. Discharge measured on June 27 at site at each site (table 2). The averages of multiple instantaneous 22 (average of 1,400 ft3/s) and site 41 (average of 385 ft3/s) discharge measurements at main-stem sites 1, 22, 41, 59, and indicated stable flow conditions on the basis of variability 69 (table 2) on days of data collection for a specific reach of multiple measurements at each site (tables 2 and 4). The were used for the instantaneous discharge measurement computed net seepage gain or loss was greater than the values that are used in the computation of gain and loss. cumulative uncertainty, indicating that seepage losses across the reach were substantial. The sum of seepage gains and 3 Reach 1, Rio Grande Below Caballo Reservoir losses within the reach was a loss of 234 ft /s (table 4). (Site 1) to Rio Grande at Haynor Bridge (Site 22) Reach 3, Rio Grande from Below Mesilla Reach 1 consists of 31.1 miles along the Rio Grande Diversion Dam (Site 41) to Rio Grande at from site 1 below Caballo Reservoir to site 22 at Haynor Anthony–EP No. 1 (Site 59) Bridge (fig. 1). Of the 22 measurement locations, a total of 9 sites had measurable discharge (2 river, 1 diversion, and Reach 3 consists of 19.8 miles along the Rio Grande and 6 inflow sites; table 3), with specific conductance and water includes sites 41 to 59 beginning below Mesilla Diversion temperature measured at each site (table 2). Zero flow was Dam and ending at the Rio Grande at Anthony–EP no. 1 (fig. observed at 1 diversion and 12 inflow sites. 1). Of the 21 measurement locations, a total of 14 sites had Uncertainty in the measurement of discharge was good measurable discharge (2 river and 12 inflow sites; table 5), at sites 1, 3A, and 22 (table 2). All measured inflow sites with specific conductance and water temperature measured were rated fair to poor. The discharge measurement at site at each site (table 2). Zero flow conditions were observed at 15 was not assigned any measurement uncertainty at the time seven inflow sites. of collection and was categorized as unspecified; a rating of Uncertainty in the measurement of discharge was good fair was assigned for the purpose of analysis on the basis of at inflow site 58 (table 2). All river sites were rated fair, and the discharge and channel conditions. Discharge measured the other measured inflow sites were rated poor. Discharge on June 26 at site 1 (average of 1,670 cubic feet per second measured on June 28 at site 41 (average of 345 ft3/s) and site [ft3/s]) and site 22 (average of 1,420 ft3/s) indicated stable 59 (average of 397 ft3/s) indicated stable flow conditions on flow conditions on the basis of variability of multiple the basis of variability of multiple measurements at each site measurements at each site (tables 2 and 3). The computed net (tables 2 and 5). The computed net gain or loss was less than seepage gain or loss was less than the cumulative uncertainty, the cumulative uncertainty, indicating that the estimated gain indicating that the estimated gain or loss within Reach 1 or loss in Reach 3 cannot be considered substantial. The sum cannot be considered substantial. The sum of seepage gains of seepage gains and losses within the reach was a gain of and losses within the reach was a loss of 66.8 ft3/s (table 3). 33.0 ft3/s (table 5). 12 Seepage Investigation on the Rio Grande from Below Caballo Reservoir, New Mexico, to El Paso, Texas, 2012

% e N ≥ N ── ── ── ── ── ── ── ── ── ── ── ── ── ── ── ── ── ── ── ── ── % (Y or N) d N

%) e ── ── ── ── ── ── ── ── ── ── ── ── ── ── ── ── ── ── ── ── ── error 6.56 (N percentage , net seepage gain (+) or Normalized G %) d ── ── ── ── ── ── ── ── ── ── ── ── ── ── ── ── ── ── ── ── ── -3.98 (N difference percentage Normalized

G ── ── ── ── ── ── ── ── ── ── ── ── ── ── ── ── ── ── ── ── ── 110 (ft³/s) for Q error (+/-) Cumulative ── ── ── ── ── ── ── ── ── ── ── ── ── 0.15 89.3 < 0.01 < 0.01 < 0.01 < 0.01 < 0.01 error measure 6,972 5,041 Squared % , discharge measured at downstream river site; Q , discharge ds

G Q ── ── ── ── ── ── ── ── ── ── ── ── ── ── ── ── ── ── ── ── ── -66.8 (ft³/s) ── ── ── ── ── ── ── ── ── ── ── ── ── (ft³/s) 9.45 0.01 0.06 0.38 0.03 discharge 83.5 71.0 < 0.001 < 0.01 ds uncertainty Q measurement %, normalized percentage difference, used to determine the difference between discharge measured at upstream and between discharge used to determine the difference %, normalized percentage difference, d %, normalized cumulative uncertainty, in percent, used to determine if a computed gain or loss exceeds errors associated in percent, used to determine if a %, normalized cumulative uncertainty, e ── ── ── ── ── ── ── ── ── ── ── ── ── (%) 5 5 8 8 8 8 5 10 10 Discharge uncertainty measurement 0 0 0 0.08 0.01 0.55 0 0 0 0 0 0 4.76 0.10 0 0 0 0 0.25 (ft³/s) 189 (Av) discharge 1,670 (Av) 1,420 (Av) measurement Instantaneous location River Diversion Diversion Inflow Inflow Inflow Inflow Inflow Inflow Inflow Inflow Inflow Inflow Inflow Inflow Inflow Inflow Inflow Inflow Inflow Inflow River Measurement Date 6/26/12 6/26/12 6/26/12 6/26/12 6/26/12 6/26/12 6/26/12 6/26/12 6/26/12 6/26/12 6/26/12 6/26/12 6/26/12 6/26/12 6/26/12 6/26/12 6/26/12 6/26/12 6/26/12 6/26/12 6/26/12 6/26/12 1,355.6 1,354.3 1,354.3 1,351.2 1,347.1 1,344.3 1,342.4 1,339.0 1,337.8 1,336.6 1,336.4 1,335.8 1,335.3 1,333.9 1,333.5 1,330.6 1,329.3 1,328.9 1,327.2 1,325.3 1,323.2 1,322.5 River mile Summary of measured discharge and the computed net seepage gain or loss in Reach 1, Rio Grande investigation, June 26, 2012.

1 3 4 5 6 7 8 9 3A 11 10 12 13 14 15 16 17 18 19 20 21 22 Site ID Table 3. Table [ID, identification number; site ID: see table 1 and figures 2 for location of sites. ft³/s, cubic feet per second; %, percent; Q loss (-). See text for equations and description of cumulative uncertainty computation; N downstream sites of a given subreach. See text for equations and definitions terms; N daily average] Av, Y, yes; N, no; ──, not applicable; measurement. See text for equations and definitions of terms; ≥, greater than or equal to; >, than; <, less with discharge Results of Seepage Investigation on the Rio Grande from Below Caballo Reservoir, New Mexico, to El Paso, Texas 13

% e N ≥ Y ── ── ── ── ── ── ── ── ── ── ── ── ── ── ── ── ── ── ── ── % (Y or N) d N

%) e ── ── ── ── ── ── ── ── ── ── ── ── ── ── ── ── ── ── ── ── 5.90 error (N percentage Normalized , net seepage gain (+) or G %) d ── ── ── ── ── ── ── ── ── ── ── ── ── ── ── ── ── ── ── ── -16.5 (N difference percentage Normalized

G ── ── ── ── ── ── ── ── ── ── ── ── ── ── ── ── ── ── ── ── 83.8 (ft³/s) for Q error (+/-) Cumulative ── ── ── ── ── ── ── ── ── 0.06 0.22 0.02 0.49 0.18 93.1 74.0 < 0.01 < 0.01 477 error 4,900 1,482 measure Squared % , discharge measured at downstream river site; Q , discharge ds

G Q ── ── ── ── ── ── ── ── ── ── ── ── ── ── ── ── ── ── ── ── -234 (ft³/s) ── ── ── ── ── ── ── ── ── 0.25 9.65 0.03 0.46 0.14 0.70 0.03 0.43 8.60 (ft³/s) 70.0 21.9 38.5 discharge ds uncertainty Q measurement %, normalized percentage difference, used to determine the difference between discharge measured at upstream and between discharge used to determine the difference %, normalized percentage difference, d %, normalized cumulative uncertainty, in percent, used to determine if a computed gain or loss exceeds errors associated in percent, used to determine if a %, normalized cumulative uncertainty, e ── ── ── ── ── ── ── ── ── (%) 5 5 8 8 5 5 10 10 10 10 10 10 Discharge uncertainty measurement 2.46 0 0 0 0.34 4.64 0 1.36 0 0 7.00 0.25 5.32 0 0 0 (ft³/s) 193 172 437 385 (Av) discharge 1,400 (Av) measurement Instantaneous location River Inflow Diversion Inflow Inflow Inflow Inflow Inflow Inflow Inflow Inflow Inflow Inflow Inflow Inflow Inflow Inflow Diversion Diversion Inflow River Measurement Date 6/27/12 6/27/12 6/27/12 6/27/12 6/27/12 6/27/12 6/27/12 6/27/12 6/27/12 6/27/12 6/27/12 6/27/12 6/27/12 6/27/12 6/27/12 6/27/12 6/27/12 6/27/12 6/27/12 6/27/12 6/27/12 1,322.5 1,320.1 1,310.0 1,300.0 1,308.8 1,304.4 1,303.9 1,301.5 1,298.6 1,296.2 1,295.1 1,293.1 1,292.9 1,291.8 1,291.2 1,291.2 1,289.1 1,287.6 1,287.6 1,287.2 1,285.7 River mile Summary of measured discharge and the computed net seepage gain or loss in Reach 2, Rio Grande investigation, June 27, 2012.

22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 36A Site ID Table 4. Table [ID, identification number; site ID: see table 1 and figures 2 for location of sites. ft³/s, cubic feet per second; %, percent; Q loss (-). See text for equations and description of cumulative uncertainty computation; N downstream sites of a given subreach. See text for equations and definitions terms; N daily average] Av, Y, yes; N, no; ──, not applicable; measurement. See text for equations and definitions of terms; ≥, greater than or equal to; >, than; <, less with discharge 14 Seepage Investigation on the Rio Grande from Below Caballo Reservoir, New Mexico, to El Paso, Texas, 2012

% e N ≥ N ── ── ── ── ── ── ── ── ── ── ── ── ── ── ── ── ── ── ── ── % (Y or N) d N

%) e ── ── ── ── ── ── ── ── ── ── ── ── ── ── ── ── ── ── ── ── 10.6 error (N , net seepage gain (+) or G percentage Normalized %) d ── ── ── ── ── ── ── ── ── ── ── ── ── ── ── ── ── ── ── ── 8.31 (N difference percentage Normalized

G ── ── ── ── ── ── ── ── ── ── ── ── ── ── ── ── ── ── ── ── 42.1 (ft³/s) for Q error (+/-) Cumulative ── ── ── ── ── ── ── 0.01 0.36 0.02 0.22 < 0.01 < 0.01 < 0.01 < 0.01 < 0.01 < 0.01 < 0.01 < 0.01 762 error 1,009 , discharge measured at downstream river site; Q , discharge measure ds Squared %

G Q ── ── ── ── ── ── ── ── ── ── ── ── ── ── ── ── ── ── ── ── 33.0 (ft³/s) ── ── ── ── ── ── ── 0.03 0.01 0.04 0.10 0.03 0.60 0.15 0.47 27.6 31.8 (ft³/s) < 0.01 < 0.01 < 0.01 < 0.01 discharge ds uncertainty Q measurement %, normalized percentage difference, used to determine the difference between discharge measured at upstream and between discharge used to determine the difference %, normalized percentage difference, d %, normalized cumulative uncertainty, in percent, used to determine if a computed gain or loss exceeds errors associated in percent, used to determine if a %, normalized cumulative uncertainty, e ── ── ── ── ── ── ── 8 5 8 (%) 10 10 10 10 10 10 10 10 10 10 10 Discharge uncertainty measurement 0 0.25 0 0.12 0.42 1.00 0.25 0 6.00 0.03 0 0 0 0.01 1.50 0 0.02 0.01 9.39 (ft³/s) 345 (Av) 397 (Av) discharge measurement Instantaneous River Inflow Inflow Inflow Inflow Inflow Inflow Inflow Inflow Inflow Inflow Inflow Inflow Inflow Inflow Inflow Inflow Inflow Inflow Inflow River location Measurement Date 6/28/12 6/28/12 6/28/12 6/28/12 6/28/12 6/28/12 6/28/12 6/28/12 6/28/12 6/28/12 6/28/12 6/28/12 6/28/12 6/28/12 6/28/12 6/28/12 6/28/12 6/28/12 6/28/12 6/28/12 6/28/12 1,285.7 1,283.9 1,283.3 1,281.5 1,281.5 1,280.7 1,280.1 1,277.5 1,275.2 1,274.3 1,274.2 1,272.4 1,270.5 1,270.4 1,270.2 1,269.3 1,268.0 1,268.0 1,267.4 1,267.1 1,265.9 River mile Summary of measured discharge and the computed net seepage gain or loss in Reach 3, Rio Grande investigation, June 28, 2012.

41 42 43 44 44A 45 46 47 48 49 50 51 52 53 54 55 56 56A 57 58 59 Site ID Table 5. Table [ID, identification number; site ID: see table 1 and figures 2 for location of sites. ft³/s, cubic feet per second; %, percent; Q loss (-). See text for equations and description of cumulative uncertainty computation; N downstream sites of a given subreach. See text for equations and definitions terms; N daily average] Av, Y, yes; N, no; ──, not applicable; measurement. See text for equations and definitions of terms; ≥, greater than or equal to; >, than; <, less with discharge Results of Seepage Investigation on the Rio Grande from Below Caballo Reservoir, New Mexico, to El Paso, Texas 15

Reach 4, Rio Grande at Anthony–EP No. 1 (Site Uncertainty in the measurement of discharge was good at 59) to Rio Grande at El Paso (Site 69) sites 60, 62, 63, and 64 (table 2). All river sites were rated fair, and measured inflow sites were rated good or poor. Discharge 3 Reach 4 consists of 16.0 miles along the Rio Grande measured on June 28 at site 59 (average of 397 ft /s) and site 69 (average of 383 ft3/s) indicated stable flow conditions and includes sites 59 to 69 beginning at the Rio Grande at on the basis of variability of multiple measurements at each Anthony–EP no. 1 and ending at the Rio Grande at El Paso site (table 6). The computed net seepage gain or loss was (fig. 1). Of the 12 measurement locations, a total of 8 sites greater than the cumulative uncertainty, indicating that losses had measurable discharge (2 river and 6 inflow sites; table 6), occurred across the reach and were substantial compared to with specific conductance and water temperature measured the uncertainties associated with measuring streamflow. The at each site (table 2). Zero flow conditions were observed at sum of gains and losses within the reach was a loss of 50.7 four inflow sites. ft3/s (table 6). 16 Seepage Investigation on the Rio Grande from Below Caballo Reservoir, New Mexico, to El Paso, Texas, 2012

% e N ≥ Y ── ── ── ── ── ── ── ── ── ── ── % (Y or N) d N

%) e ── ── ── ── ── ── ── ── ── ── ── 10.2 error (N , net seepage gain (+) or G percentage Normalized %) d ── ── ── ── ── ── ── ── ── ── ── -11.7 (N difference percentage Normalized

G ── ── ── ── ── ── ── ── ── ── ── 44.1 (ft³/s) for Q error (+/-) Cumulative ── ── ── ── 0.03 0.03 0.03 0.30 0.40 0.79 error 939 measure 1,009 , discharge measured at downstream river site; Q , discharge Squared % ds

G Q ── ── ── ── ── ── ── ── ── ── ── -50.7 (ft³/s) ── ── ── ── 0.16 0.18 0.18 0.55 0.64 0.89 (ft³/s) 31.8 30.6 discharge ds uncertainty Q measurement %, normalized percentage difference, used to determine the difference between discharge measured at upstream and between discharge used to determine the difference %, normalized percentage difference, d %, normalized cumulative uncertainty, in percent, used to determine if a computed gain or loss exceeds errors associated in percent, used to determine if a %, normalized cumulative uncertainty, e ── ── ── ── 8 5 5 5 5 8 (%) 10 10 Discharge uncertainty measurement 0 3.21 0 3.66 3.62 0 6.36 0 8.88 (ft³/s) 11.0 397 (Av) 383 (Av) discharge measurement Instantaneous River Inflow Inflow Inflow Inflow Inflow Inflow Inflow Inflow Inflow Inflow River location Measurement Date 6/28/12 6/28/12 6/28/12 6/28/12 6/28/12 6/28/12 6/28/12 6/28/12 6/28/12 6/28/12 6/28/12 6/28/12 1,265.9 1,265.9 1,264.7 1,264.0 1,258.6 1,258.0 1,257.6 1,256.0 1,254.1 1,250.9 1,250.3 1,249.9 River mile Summary of measured discharge and the computed net seepage gain or loss in Reach 4, Rio Grande investigation, June 28, 2012.

59 59A 60 61 62 63 64 65 66 67 68 69 Site ID Table 6. Table [ID, identification number; site ID: see table 1 and figures 2 for location of sites. ft³/s, cubic feet per second; %, percent; Q loss (-). See text for equations and description of cumulative uncertainty computation; N downstream sites of a given subreach. See text for equations and definitions terms; N daily average] Av, Y, yes; N, no; ──, not applicable; measurement. See text for equations and definitions of terms; ≥, greater than or equal to; >, than; <, less with discharge References Cited 17

Summary Oberg, K.A., Morlock, S.E., and Caldwell, W.S., 2005, Quality assurance plan for discharge measurements using acoustic Doppler current profilers: U.S. Geological Survey Scientific A seepage investigation was conducted in 2012 on the Investigations Report 2005–5183, 35 p. [Also available at Rio Grande from below Caballo Reservoir, New Mexico, to http://pubs.usgs.gov/sir/2005/5183/SIR_2005-5183.pdf.] El Paso, Texas, by the U.S. Geological Survey, in cooperation with the New Mexico Interstate Stream Commission. A total Rantz, S.E., and others, 1982, Measurement and computation of 73 sites including river channel, diversions, and inflows of streamflow, volume 1—Measurement of stage and associated with irrigation systems were selected for four discharge: U.S. Geological Survey Water-Supply Paper reaches on the Rio Grande. The most upstream site was 2175, 284 p. [Also available at http://pubs.usgs.gov/wsp/ located immediately below Caballo Reservoir, and the most wsp2175/.] downstream site was located at the U.S. Geological Survey Sauer, V.B., and Meyer, R.W., 1992, Determination of error in streamgage Rio Grande at El Paso. individual discharge measurements: U.S. Geological Survey Discharge was measured at 40 of the 73 sites during Open-File Report 92–144, 21 p. [Also available at http:// June 26–28, 2012, during the irrigation season at high flow. pubs.usgs.gov/of/1992/ofr92-144/.] Cumulative gains or losses, which include estimated seepage Simonds, F.W., and Sinclair, K.A., 2002, Surface water- gains or losses, were calculated for each of the four reaches by groundwater interactions along the Lower Dungeness River using the instantaneous discharge values for each site. Reach and vertical hydraulic conductivity of streambed sediments, 1 had a calculated loss of 66.8 cubic feet per second (ft3/s) that Clallam County, Washington, September 1999–July 2001: was less than the estimated measurement uncertainty. Reach U.S. Geological Survey Water-Resources Investigations 3 2 had a calculated loss of 234 ft /s that was greater than the Report 02–4161, 60 p. estimated measurement uncertainty. Reach 3 had a calculated gain of 33.0 ft3/s that was less than the estimated measurement Turnipseed, D.P., and Sauer, V.B., 2010, Discharge uncertainty. Reach 4 had a calculated loss of 50.7 ft3/s that was measurements at gaging stations: U.S. Geological Survey greater than the estimated measurement uncertainty. Techniques and Methods, book 3, chap. A8, 87 p. [Also available at http://pubs.usgs.gov/tm/tm3-a8/.]

Wheeler, J.D., and Eddy-Miller, C.A., 2005, Seepage References Cited investigation on selected reaches of Fish Creek, Teton County, Wyoming, 2004: U.S. Geological Survey Scientific Investigations Report 2005–5133, 22 p. Bureau of Reclamation, 2008, Operating agreement for the Rio Grande Project: Bureau of Reclamation, 23 p. [Also Wilberg, D.E., and Stolp, B.J., 2005, Seepage investigation available at http://www.usbr.gov/uc/albuq/rm/RGP/pdfs/ and selected hydrologic data for the Escalante River Operating-Agreement2008.pdf.] drainage basin, Garfield and Kane Counties, Utah, 1909– 2002: U.S. Geological Survey Scientific Investigations Crilley, D.M., Matherne, A.M., Thomas, Nicole, and Falk, Report 04–5233, 39 p. [Also available at http://pubs.usgs. S.E., 2013, Seepage investigations of the Rio Grande from gov/sir/2004/5233/PDF/SIR2004_5233.pdf.] below Leasburg Dam, Leasburg, New Mexico, to above Wilberg, D.E., Swenson, R.L., Slaugh, B.A., Howells, J.H., American Dam, El Paso, Texas, 2006–13: U.S. Geological and Christiansen, H.K., 2001, Seepage investigation for Survey Open-File Report 2013–1233, 34 p. Leap, South Ash, Wet Sandy, and Leeds Creek in the Pine Hendricks, E.L., 1964, Compilation of records of surface Valley Mountains, Washington County, Utah, 1998: U.S. Geological Survey Water-Resources Investigations Report waters of the United States, October 1950 to September 01–4237, 42 p. 1960: U.S. Geological Survey Water-Supply Paper 1732, 574 p. [Also available at http://pubs.usgs.gov/wsp/1732/ Wilde, F.D., and Radtke, D.B., eds., variously dated, Field report.pdf.] measurements: U.S. Geological Survey Techniques of Water-Resources Investigations, book 9, chap. A6. [Also Kilpatrick, F.A., and Schneider, V.R., 1983, Use of flumes in available at http://water.usgs.gov/owq/FieldManual/ measuring discharge: U.S. Geological Survey Techniques Chapter6/Ch6_contents.html.] of Water-Resources Investigations, book 3, chap. A14, 46 p. [Also available at http://pubs.usgs.gov/twri/twri3-a14/.]

Nolan, K.M., and Shields, R.R., 2000, Measurement of stream discharge by wading: U.S. Geological Survey Water- Publishing support provided by Resources Investigations Report 00–4036, CD-ROM. Lafayette Publishing Service Center 18 Seepage Investigation on the Rio Grande from Below Caballo Reservoir, New Mexico, to El Paso, Texas, 2012 Gunn and Roark—Seepage Investigation on the Rio Grande from Below Caballo Reservoir, New Mexico, to El Paso, Texas, 2012—SIR 2014–5197 ISSN 2328-0328 (online) http://dx.doi.org/10.3133/sir20145197